Unfortunately,....I haven't tested any of them so far.
But I've checked with the Super Converter, and it does also convert audio files to mp3.
The files supported are:
ac3, amr, mp2, mp3, mp4, ogg, ra, wav, wma,......and maybe some others as well.
So, my suggestion would be to try first the Super converter mentioned in my post above.....try to convert the audio file to either mp3 or wav.
If that doesn't work out, try any of the programs you can get for free at Nonags.....since they are free to download, you will only waste some time in the worst case......though I believe already with the Super converter you should have some success......
Cheers